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Component Templates

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Under Tapestry, a component template is a Under Tapestry, a component template is the file that contains the markup for that page or a component.

Component templates are well formed XML documents. That means that every open tag must have a matching close tag, every attribute must be quoted, and so forth.

...

Note: At runtime, Tapestry parses the documents and only checks for wellformedness. Even when the document has a DTD or schema, there are no validity checks.

For the most part, these templates are standard HTML/XHTML; Tapestry extensions to ordinary markup are provided in the form of a Tapestry namespace.

We'll cover the specific content of templates shortly, first a few details about connecting a component to its template.

Template Location

Component templates are stored with the component class file. The files have a ".tml" extension (i.e., Tapestry Markup Language), and are stored in the same package as corresponding component class.

Under a typical Maven directory structure, the Java class for a component might be src/main/java/org/example/myapp/components/MyComponent.java. The corresponding template will be src/main/resources/org/example/myapp/components/MyComponent.tml.

...

XML namespace (xmlns):

Code Block

language	xml
title	A template for a page

<html t:type="layout" xmlns:t="http://tapestry.apache.org/schema/tapestry_5_4.xsd">
    <h1>Bonjour from HelloWorld component.</h1>
</html>

We'll cover the specific content of templates shortly, but first a few details about connecting a component to its template.

Template Location

A component template shares the same name as its corresponding class file, but with a ".tml" ending (i.e., Tapestry Markup Language), and is stored in the same package as the corresponding component class.

Under a typical Maven directory structure, the Java class and template files for a component might be:

Java class:

src/main/java/org/example/myapp/

...

components/

...

MyComponent.java

...


Template:	`src/main/resources/org/example/myapp/`

...

components/

...

MyComponent.tml

...

The template and the compiled class will be packaged together in the WEB-INF/classes folder of the application WAR.

For pages (not components), a second location will be searched: in the web application context. The location is based on the logical name of the page, in the previous example, the template would be MyPage.tml in the root folder of the web application.

A template on the classpath takes precedence over a file in the web application context.

Warning

Allowing pages to store their template in the web context is a feature that may go away at some point. It was included as a way for HTML designers to edit template directly and live preview the template directly, without executing the Tapestry application. This comes with a large number of limitations and leads to a false sense of security that a template that previews correctly will render properly (this is not always the case).

In certain cases, Tapestry will simplify the the logical name of a page. For example, the page class org.example.pages.address.CreateAddress will be given a logical name of "address/Create" (the redundant "Address" is removed as a suffix). However, this only affects how the page is referenced in URLs; the template file will still be CreateAddress.tml, whether on the classpath, or as address/CreateAddress.tml (in the web context).

Likewise, the Java class and template files for a page might be:

Java class:	`src/main/java/org/example/myapp/pages/MyPage.java`
Template:	`src/main/resources/org/example/myapp/pages/MyPage.tml`

The template and the compiled class will be packaged together in the WEB-INF/classes folder of the application WAR.

For pages (but not other components), a second location will be searched: in the web application context. The location is based on the logical name of the page, in the previous example, the template would be MyPage.tml in the root folder of the web application.

A template on the classpath takes precedence over a file in the web application context.

Warning
Allowing pages to store their template in the web context is a feature that may go away at some point. It was included as a way for HTML designers to edit template directly and live preview the template directly, without executing the Tapestry application. This comes with a large number of limitations and leads to a false sense of security that a template that previews correctly will render properly (this is not always the case)
Info
Tapestry actually creates multiple names for the name page: address/Create and address/CreateAddress are both synonymous. You can user either in Java code that refers to a page by name, or as the page parameter of a PageLink.

Template Localization

Main Article: Localization

Templates are handled in much the same way as individual files of a component's message catalog: the effective locale is inserted into the name of the file. Thus a German users will see the content generated from MyPage_de.tml and French users will see content generated from MyPage_fr.tml. When no specific localization is available, the default location (MyPage.tml) is used.

Info

It is necessary to enable support for a locale

before Tapestry will attempt to localize to that locale. This requires configuration in your application module (usually AppModule.java); if you are using the Tapestry Quickstart archetype, only locale "en" will be enabled by default.

...

As mentioned above, component templates are well-formed XML documents. This means that if you want to use any Named HTML entities (such as \& \ < > ©& < > ©), you must use an HTML or XHTML doctype in your template (starting in 5.3, this is more-or-less automatic, see notes below). If you choose to use (X)HTML doctypes in your templates, they will be passed on to the client in the resultant (X)HTML. Note that if your pages are composed of multiple components, each with a template, and each template contains a doctype declaration, only the first doctype encountered by the template parser will be passed on to the client.

It should also be noted that even though *X*HTML DTDs are valid XML DTDs, HTML DTDs aren't. This means that HTML doctypes cannot be used by XML parsers. Tapestry works around this limitation internally by using XHTML DTDs to parse templates that use HTML DTDs. This internal mapping is possible because XHTML 1.0 is nothing more than "a reformulation of the three HTML 4 document types as applications of XML 1.0," as per the W3C. Don't worry though – the original HTML 4 doctype will still be emitted to the client!

The following doctypes are the most common (X)HTML doctypes:

Code Block

	xml
	xml

<!DOCTYPE html>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
   "http://www.w3.org/TR/html4/strict.dtd">

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">

<!DOCTYPE html>

That last The first one is for HTML5 and only works in for HTML5 and is recommended for Tapestry 5.2.5 and later versions. In earlier versionsversions prior to Tapestry 5.2.5, Tapestry didn't support the HTML5 doctype directly (see TAP5-1040), but there's a partial work-around: just add the following to your page class (or your layout class, if you use one) instead of adding the doctype to your template (.tml) files:

...

the

...

HTML5

...

doctype directly (but see the comments at TAP5-1040 for a work-around).

Since

since	5.3

Tapestry 5.3 introduces introduced two significant improvements to template Doctypes. A template without a <!DOCTYPE> is parsed as if it had the HTML Doctype (<!DOCTYPE html>{{}}). In fact, Tapestry creates an in-memory copy of the template that includes the doctype. A template with the HTML Doctype (<!DOCTYPE html>{{}}) is parsed as if it had the XHTML transitional Doctype. In fact, Tapestry creates an in-memory copy of the template that replaces the <!DOCTYPE> line. This applies as well to a template without any Doctype, in which case the XHTML transitional Doctype is inserted at the top. In either case, this means you can use arbitrary HTML entities, such as {{©}} or {{ }} without seeing the XML parsing errors that would occur in earlier releases.

The Tapestry Namespace

Component templates should include the Tapestry namespace, defining it in the root element of the template.

Code Block

xml

language	xml


<html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_34.xsd">
    <head>
        <title>Hello World Page</title>
    </head>
    <body>
        <h1>Hello World</h1>
    </body>
</html>

...

For backwards compatibility, you may continue to use the old namespace URIs: http://tapestry.apache.org/schema/tapestry_5_0_0.xsd or http://tapestry.apache.org/schema/tapestry_5_1_0.xsd. However or http://tapestry.apache.org/schema/tapestry_5_3.xsd

However, the following elements added, as part of Tapestry 5.1, will not work with the 5_0_0.xsd:

...

The 5_3.xsd fixes some minor bugs in the 5_1_0.xsd, but is functionally equivalent_0.xsd, but is functionally equivalent; 5_3.xsd and 5_4.xsd are identical.

Tapestry Elements

Tapestry elements are elements defined using the Tapestry namespace prefix (usually "t:").

All other elements in your templates should be in the default namespace, with no prefix (with the possible exception of any Library Namespaces (described below).

There are a certain number of Tapestry elements, listed below, that act as template directives; beyond that, any element in the Tapestry namespace will be a Tapestry component.

...

In many cases, a component is designed to integrate have its template with its container's templateintegrate with, or "wrap around", the containing component.

The <t:body> element is used to identify where, within a component's template, its body (from the container's template) is to be rendered.

...

The following example is a Layout component, that which adds basic HTML elements around the page-specific content:

Code Block

xml

language	xml


<html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd">
    <head>
        <title>My Tapestry Application</title>
    </head>
    <body>
        <t:body/>
    </body>
</body>
</html>
/html>

That "<t:body/>" element marks where the containing page's content will be inserted. A page would then use this component as follow:

info

Code Block

xml

language	xml


<t:layout<html t:type="layout" xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd">

  My Page Specific Content

</t:layout>html>

In this example, t:layout creates a Layout component (more on this shortly).

When the page renders, the page's template and the Layout component's template are merged together:

Code Block

xml

language	xml


<html>
  <head>
    <title>My Tapestry Application</title>
  </head>
  <body>
    My Page Specific Content
  </body>
</html>

...

A <t:container> element contains markup without being considered part of the template. This is useful for components that render several top level tags, for example, a component that renders several columns within a table row:

Code Block

xml

language	xml


<t:container xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd">
  <td>${label}</td>
  <td>${value}</td>
</t:container>

...

A block may be anonymous, or it may have an id (specified with the id attribute). Non-anonymous blocks Only blocks with an id may be injected into the component.

Warning
A <t:block> must be in the Tapestry namespace, but the id attribute should not be. This is different from components in the template, where the t:id attribute that defines the component id must be in the Tapestry namespace.

...

The <t:parameter> Element

Note
This element has been was deprecated starting in Tapestry 5.1 (but is still fully supported, for backwards compatibility)and removed in 5.3. Use parameter namespaces (below) instead.

A <parameter> element is a special kind of block. It is placed inside the body of an embedded component. The block defined by the <parameter> is passed to the component. <parameter> includes a mandatory name attribute to identify which parameter of the component to bind.

Example:

...

the component to bind.

The <t:content> Element

<t:content> marks a portion of the template as the actual template content; any markup outside the <t:content> element is ignored. This is useful for eliminating portions of the template that exist to support WYSIWYG preview of the template.

...

Support for the <t:content> element was adding in Tapestry release 5.1. You must use the http://tapestry.apache.org/schema/tapestry_5_1_04.xsd or http://tapestry.apache.org/schema/tapestry_5_3.xsd (or ...5_3 or ...5_1_0.xsd) namespace URI for content to be recognized (otherwise you will see an error about a missing "content" component).

...

Support for the <t:remove> element was added in Tapestry release 5.1. You must use the http://tapestry.apache.org/schema/tapestry_5_1_04.xsd or http://tapestry.apache.org/schema/tapestry_5_3.xsd (or ...5_3 or ...5_1_0.xsd) namespace URI for remove to be recognized (otherwise you will see an error about a missing "remove" component).

...

Another option when rendering output is the use of expansions. Expansions are special strings that may be embedded in template bodies, and borrow some syntax from the Ant build tool.

Code Block

xml

language	xml


  Welcome, ${userId}!

Here, ${userId} is the expansion. In this example, the userId property of the component is extracted, converted to a string, and streamed into the output.

Expansions are allowed inside text, and inside attributes of ordinary elements, and component elements. For example:

Code Block

xml

language	xml


  <img src="${request.contextPath}/images/catalog/product_${productId}.png"/>

...

Caution: if the content comes from an untrusted source (like a public user), be sure to filter it before providing it to OutputRaw. Otherwise you've got a potential cross-site scripting vulnerability.

...

Embedded Components

An embedded component is identified within the template as an element in the t: namespace. Example:

Code Block

xml

language	xml


  You have ${cartItems.size()} items in your cart.
  <t:actionlink t:id="clear">Remove All</t:actionlink>.

...

Embedded components may have two Tapestry-specific parameters:

id: A unique id for the component (within its container).
mixins: An optional comma separated list of mixins for the the component.

...

The open and close tags of a Tapestry component element define the body of the component. It is quite common for additional components to be enclosed in the body of another component:

Code Block

xml

language	xml


<t:form>
  <t:errors/>
  <t:label for="userId"/>
  <t:textfield t:id="userId"/>
  <br/>
  <t:tablelabel for="password"/>
  <t:passwordfield t:id="password"/>
  <br/>
  <input type="submit" value="Login"/>
</t:form>

...

Info
When using a component library, the library will map its components to a virtual sub-folder of the application. The same naming mechanism works whether its is a real sub-folder or a component library sub-folder.

Anchor

	LibraryNamespaces
	LibraryNamespaces

Library Namespaces

If you are using many components from a common Tapestry component library, you can use a special namespace to simplify references to those components.

...

Borrowing from the above example, all of the following are equivalent:

Code Block

xml

language	xml


<html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd" xmlns:a="tapestry-library:ajax">

  <t:ajax.dialog/>

  <span t:type="ajax/dialog"/>

  <a:dialog/>

  . . .

...

Invisible instrumentation involves using namespaced id or type attributes to mark an ordinary (X)HTML element as a component. For example:

Code Block

xml

language	xml


<html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd">
<p>
    Merry Christmas:
    <span t:type="Count" end="3">
        Ho!
    </span>
</p>

...

via the t:type attribute in the containing template, as in the above example, or
within the containing component's Java class using the @Component annotation (and using the t:id attribute on the element in the template). The Component annotation is attached to a field; the type of the component is determined by either the type of the field or the type attribute of the Component annotation.

In most cases, it is merely an aesthetic choice whether to use invisible instrumentation in your templates. However, in a very few cases the behavior of the component is influenced by your choice. For example, when your template includes the Loop component using the invisible instrumentation approach, the original tag (and its informal parameters) will render repeatedly around the body of the component. Thus, for example:

Code Block

xml

language	xml


  <table>
    <tr t:type="loop" source="items" value="item" class="prop:rowClass">
      <td>${item.id}</td>
      <td>${item.name}</td>
      <td>${item.quantity}</td>
    </tr>
  </tabel>

...

Anchor

	parameter-namespaces
	parameter-namespaces

Parameter Namespaces

Main Article: Component Parameters

Parameter namespaces are a new feature (introduced in Tapestry 5.1. They ) are a more concise way of passing parameter blocks to components.

You must define a special namespace, usually given with the prefix "p":

Code Block

xml

language	xml


<html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd" xmlns:p="tapestry:parameter">
  . . .

With the "tapestry:parameter" namespace defined, you can pass block using the "p:" prefix and an element name that matches the parameter name:

Code Block

xml

language	xml


<t:if test="loggedIn">
  Hello, ${userName}!
  <p:else>
    Click <a t:type="actionlink" t:id="login">here</a> to log in.
  </p:else>
</t:if>

This example passes a block of the template (containing the ActionLink component and some text) to the If component as parameter else. In the If component's reference page you'll see that else is parameter of type Block.

Name-spaced parameter elements are not allowed to have any attributes. The element name itself is used to identify the parameter of the component to bind.

...

This approach has certain efficiency advantages on both the server (less processing to render the page) and on the client (fewer characters to parse). Tools such as FireBug Firefox Developer Tools and Chrome Developer Tools are useful for allowing you to view the rendered HTML on the client properly.

...

The xml: namespace prefix is built into all XML documents, there is no special configuration (as there is with the Tapestry namespace).

For example:

Code Block

xml

language	xml


  <ul class="navmenu" xml:space="preserve">
    <li t:type="loop" t:source="pages" t:value="var:page">
      <t:pagelink page="var:page">${var:page}</t:pagelink>
    </li>
  </ul>

This will preserve the whitespace between the <ul> and <li> elements, and between the (rendered) <li> elements and the nested <a> elements. For example, the output may look something like:

Code Block

xml

language	xml


  <ul>
    <li>
      <a href="showcart>ShowCart</a>
    </li>
    <li>
      <a href="viewaccount">ViewAccount</a>
    </li>
  </ul>

With normal whitespace compression, you would see the following rendered output:

Code Block

xml

language	xml


  <ul><li><a href="showcart">ShowCart</a></li><li><a href="viewaccount">ViewAccount</li></ul>

...

Marks a point in a template that may be replaced. A unique id (case insensitive) is used in the template and its sub-templates to link extension points to possible overrides.

Code Block

xml

language	xml


  <t:extension-point id="title">
    <h1>${defaultTitle}</h1>
  </t:extension-point>

...

Replaces an extension point from a parent template. <t:replace> may only appear as the immediate child of a root <t:extend> element.

Code Block

xml

language	xml


<t:extend xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd">
  <t:replace id="title">
    <h1><img src="${context:images/icon.jpg}"/>
    Customer Service</h1>
  </t:replace>
</t:extend>

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Key

Component Templates

Template Location

Template Location

Template Localization

The Tapestry Namespace

Tapestry Elements

The <t:parameter> Element

The <t:content> Element

Embedded Components

Library Namespaces

Parameter Namespaces

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Versions Compared

Old Version 25

New Version Current

Key

Component Templates

Template Location

Template Location

Template Localization

The Tapestry Namespace

Tapestry Elements

The <t:parameter> Element

The <t:content> Element

Embedded Components

Library Namespaces

Parameter Namespaces